We report on a computer simulation and integral equation study of a simple model of patchy spheres, each of whose surfaces is decorated with two opposite attractive caps, as a function of the fraction of covered attractive surface. The simple model explored—the two-patch Kern–Frenkel model—interpolates between a square-well and a hard-sphere potential on changing the coverage . We show that integral equation theory provides quantitative predictions in the entire explored region of temperatures and densities from the square-well limit chi=1.0 down to chi~0.6. For smaller , good numerical convergence of the equations is achieved only at temperatures larger than the gas-liquid critical point, where integral equation theory provides a complete description of the angular dependence. These results are contrasted with those for the one-patch case.
